Slip control system for motor vehicle

Abstract

A slip control system for a motor vehicle controls slips in driving wheels and includes a sensor for detecting a slip ratio of each driving wheel and a traction control system for decreasing a slip of each driving wheel by controlling a driving force transmitted to each driving wheel so that the slip ratio of each driving wheel is at least equal to a predetermined desired slip ratio when the slip ratio of the driving wheel becomes equal to the desired slip ratio. An automatic transmission control system controls an automatic transmission by using a first shift property for a normal operation, and a second shift property for a traction control operation which is adapted to determine a relative higher speed stage. A device is provided for switching the first shift property to the second shift property when the traction control operation is started by the traction control system.

What is claimed is: 
     
       1. A slip control system for a motor vehicle controlling slips in driving wheels comprising: means for detecting a slip ratio of each driving wheel;   traction control means for decreasing a slip of each driving wheel by controlling a driving force transmitted to each driving wheel so that the slip ratio of each driving wheel is at least equal to a predetermined desired slip ratio when the slip ratio of the driving wheel becomes equal to the desired slip ratio;   means for controlling an automatic transmission by using a first shift property for a normal operation and a second shift property for a traction control operation which is adapted to determine a relative higher speed stage;   means for switching the first shift property to the second shift property when the traction control operation is started by the traction control means; and   means for prohibiting the automatic transmission from shifting up in a predetermined time after said traction control means starts to control the driving force.   
     
     
       2. A slip control system for a motor vehicle in accordance with claim 1 in which said means for prohibiting includes means for delaying the shifting up of the automatic transmission during the predetermined time when said means for controlling said automatic transmission determines the shifting up to be based on the second shift property. 
     
     
       3. A slip control system for a motor vehicle in accordance with claim 1 in which said first shift property includes a first shift map and said second shift property includes a second shift map. 
     
     
       4. A slip control system for a motor vehicle in accordance with claim 3 in which said second shift map includes no shift line from a first stage to a second stage. 
     
     
       5. A slip control system for a motor vehicle in accordance with claim 1 in which said prohibiting means includes means for delaying the switching from the first shift property to the second shift property in the predetermined time.